Their heated exchange was posted online and at one point, an angry Minaj is said to have raged: "If I had a gun I would shoot her (Carey)."

The reality show's executive producer Nigel Lythgoe quickly blasted the claims, branding them "absolute rubbish", but the Hero singer was so alarmed by the alleged threats, she beefed up her security team out of fear for her twin babies, Monroe and Moroccan.

Speaking out about the incident for the first time, Carey tells Barbara Walters, the host of US news show 20/20: "It felt like an unsafe work environment. Anytime anybody's reeling threats at somebody, you know, that's just not appropriate. Sitting there on the road with two babies, I'm not gonna take any chances, so yeah I did hire more security."

The pair has since patched up its differences, and Carey, who was paid a reported $US18 million ($A17.22 million) to appear on the series, insists she is now just focusing on her role as a judge and mentor.

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She adds: "For me, ultimately this is about the contestants. I've been blessed with my dream (for) more than half my life so I want to help give that back to someone else."

Meanwhile, the Starships singer has since aired her side of the story on her reality show Nicki Minaj: My Truth, stating: "Twenty minutes before that (argument) happened, she egged me on... In life, you react, and what you saw was a reaction."

And the feud is still simmering - Minaj recently took another shot at Carey in an interview with The Hollywood Reporter, picking on her fellow diva's costume choices.

"I can think of at least one other person that shows more cleavage and skin than me," she said.